This invention relates to exercising devices which utilize the gyroscopic effect of a rapidly spinning mass to develop or strengthen selected muscles of the human body for purposes of, for example, athletic training, exercise or physical therapy.
In conventional weight training for athletes, heavy weights and dumbbells are used which, because of the strong force of gravity pulling them downward, provide a resistive force against which muscles may be exercised. Although exercising with such weights and dumbbells has many benefits, the variety and types of muscles which may be exercised are restricted.
Exercising systems based solely on weight principally benefit the flexor and extensor muscles of the body, since the weight lifting or thrusting motion consists basically of overcoming the force of gravity along a straight line. Muscle groups such as those associated with circular twisting motion of the arms and wrists, or of the feet and legs, are not appreciably exercised by use of conventional weights.
It has been known in the prior art that the precession or gyroscopic effect of a rapidly spinning mass, which is the basis of operation of gyroscopes and similar devices, may be used for purposes of exercise. This effect is capable of producing a strong torque if the user attempts to move the mass in a way which rotates its spin axis.
U.S. Pat. No. 3,617,056, issued Nov. 2, 1971 to Herbold, discloses a dumbbell utilizing the precessional effect of a spinning mass. In the embodiment shown in FIGS. 3 and 5 of the drawing of Herbold, a dumbbell is provided having two parallel rotating discs at the two ends of a handle bar. The discs are heavy weights enclosed within a housing and freely rotatable about the axis of the handle bar. An accessory drive shown in FIG. 4 is used to "spin up" the disc weights within the dumbbell.
Although this gyroscopic dumbbell exerciser is an advance upon simple weighted dumbbells, it is not capable of taking full advantage of the precession effect. In a typical exercising motion, the dumbbell may be grasped by the handle bar, with the arm fully extended, and with the palm of the hand facing upward. Exercise is obtained by flexing the muscles of the arm to lift the dumbbell by an upward swinging motion of the arm which swings the hand and the dumbbell through an upward arc. Since this upward lifting (curl) motion does not change the spin axis of the spinning discs, there is no precession effect produced by this exercising movement and in this common type of exercise the gyroscopic dumbbell behaves like a simple weighted dumbbell.
In the embodiment shown in FIGS. 1 and 2 of Herbold, both a cup-shaped rotatable mass 8 and a self-contained motor 4 for rotating the mass are incorporated within a housing 1 which is surrounded by a circular handgrip 2 connected to the housing by three radial spokes 3. The motor 4 closely surrounds the spin axis of the rotatable mass 8, so that any gyroscopic effect of the motor rotor is negligible, reducing the gyroscopic exercise "efficiency" of the device. The handgrip, which has the general shape of a steering wheel, is adapted for two-handed use, and cannot readily be held in one hand.
Other exercise devices utilizing gyroscopic and other effects of a rotating mass are disclosed in the following U.S. Pat. Nos.: Newkirk et al., 1,058,786; Silkebakken et al., 4,150,580; Kellogg, 850,938; Dean, 3,482,835; Vetter, 3,841,627; Klose, 3,901,503.
Accordingly, an object of the present invention is to provide an improved gyroscopic type of exercise device.